Introduction of nucleic acid (transfection) into a cell of a potential host, which is one of approaches for genetic research, is a useful method to analyze gene function. In particular, the observation of changes in cell function after gene expression or after inhibiting the expression of genes has been conducted by introducing plasmid DNAs, viral vectors, antisense oligonucleotides, siRNAs and the like into cells. As of now various kinds of genomes have been decoded, and technologies to analyze those gene functions at the cell level attract the attention in genetic research. The development of apparatus to analyze cell function, for example, recent multi-imaging analyzers and plate readers provide short time analysis of cell function of multiple samples cultured in multi-well plates, so that the cell level analysis of gene function combining the transfection of nucleic acid with apparatus for analyzing cell function is increasing its importance.
However, the conventional methods for introducing nucleic acid is conducted by seeding cells in a culture container, culturing them and then infecting them with viral vectors into which the nucleic acid to be introduced have been integrated, or by mixing the nucleic acid with an introducing agent and adding the mixture into a culture medium, thus the preparation step of the mixture of viral vectors or nucleic acid with an introducing agent is needed each time, making the methods complicated and exceedingly laborious especially in a case introducing nucleic acid of multiple samples from diverse kinds. Further, there has been a problem in those methods that cell function can not be accurately determined due to the cytotoxicity of viruses or introducing agents, which interfere with, for example, cell growth and apoptosis assays.
Accordingly, a transfection method has been developed, wherein genes are placed on a slide glass in advance, an introducing agent is added at the time of use and then cells are seeded there (Non-patent document 1).
Further, a gene screening method based on changes in cell function has been reported, wherein the changes are presented by facilitation or inhibition of the gene expression, using a cell transfection array in which plates are precoated with the mixture of atelocollagen and nucleic acid (Non-patent document 2, patent document 1). (Non-patent document 1) Nature 411, 107, 2001 (Non-patent document 2) Biochemical and Biophysical Research Communications 289, 1075-1081 (2001) (Patent document 1) Pamphlet of International Publication WO 03/000297